This invention relates generally to internal combustion engine inserts, and more specifically, to a valve seat configuration and installation process that establishes secure seat retention in an engine where the engine and seat have dissimilar coefficients of expansion.
The field of manufacturing internal combustion engines has slowly developed over the past two centuries. Today, various materials are used in the engines and the engine components in an attempt to reduce weight, dissipate heat, and increase durability and reliability. For a long time the sealing surface of the intake and exhaust valves have employed special materials for the valves and perimeter of the manifold opening, known as a seat, to ensure proper selective fluid flow and sealing. With varied materials come varied physical properties, some which are desired, such as durability and heat dissipation, and some that are not desirable, such as differing thermal expansion. In particular, different coefficients of thermal expansion of the engine material of the part of the engine where the seat is placed and the seat material has been a problem to the field for a long time.
When the engine in which the seat is seated and the seat have differing coefficients of expansion, when the engine gets hot it expands at a different rate than the seat. Additionally, when the engine and seat get extremely cold, and then are started, the parts heat at different rates. In either scenario seats may become loose and interfere with the function of the valve and pistons, causing severe damage. Even recently, a major engine builder noted difficulty with “seats loosening up and dropping out in some of its late model 4.7 liter and 5.7 liter . . . engines” in an article in “Engine Builder Magazine,” entitled “Valve Seat Selection, Finishing & Materials.” This is in spite of the industry accepted best practice of heating the engine to over 200 degrees in a furnace, while chilling the seats with dry ice or liquid nitrogen, in order to press-fit the temporarily shrunk seat into the temporarily enlarged bore in the engine. Even with this augmented interference fit, experts in the field are still experiencing difficulties.
Prior solutions have looked to include a threaded interface between the seat and the engine, but such configurations are found to creep apart during expansion and contraction cycles. Alternative prior solutions have looked at deformation of the seat upon insertion into the engine, but such configurations are found to also creep apart during expansion and contraction cycles. Additionally, a material malable enough to deform will deform again under operational conditions.
It would be an improvement to the field of art to have the valve seat and engine design where the interference fit between the engine and the seat does not greatly diminish with extreme temperatures and the rapid change in temperatures.